Analyses Of The Incidence Trend Of Class B Infectious Diseases In China Based On Dynamic Factor Model In 2004-2015

Objective: To model the incidence of class B infectious diseases by the routes of transmission and to model the incidence of tuberculosis by economic regions in China from 2004 to 2015 with Dynamic Factor Models,respectively.A common factor was extracted from the incidences of diseases with each of the model.The variation trend of infectious diseases with different transmission routes was analyzed,and the influence of economic level on the common trend of tuberculosis incidence in different regions was also analyzed according to the common factors,which would broaden the thinking for the research on infectious diseases and provide more reference information for the prevention and control of infectious diseases in practical work.Materials and methods: The number of cases of each class b infectious disease in each month from 2004 to 2015 was collected through the official website of the public health data center.The number of resident population and the number of population in each province at the end of each year were obtained from the website of the national bureau of statistics.The time series of the monthly incidence of class B infectious diseases and tuberculosis in each province were calculated.At the same time,the GDP data of each province from 2004 to 2015 were also inquired from the website of national bureau of statistics,and the time series data of per capita monthly GDP of each economic region were calculated.The dynamic factor model was used to model the incidence of class B infectious disease from 2004 to 2015 according to the four transmission routes,and a common factor was extracted from each route.The same method was used to model the incidence of tuberculosis and extract the common factors according to economical regions.Cross-correlation analysis and linear regression model were used to analyze the influence of e conomic level on the common trend of tuberculosis incidence in each economical region.Results: From 2004 to 2015,a total of 40027468 cases of class B infectious diseases were reported in China.The three diseases with the highest average annual morbidity are hepatitis B,tuberculosis and syphilis,with the average annual morbidity of 78.706/100000,76.962/100000 and 22.378/100000,respectively.After excluding some diseases,Dynamic Factor Models were established for 18 class B infectious diseases according to four transmission routes,including 4 diseases transmitted through respiratory tract(tuberculosis,measles,cerebral hemorrhage and pertussis),3 diseases transmitted through the digestive tract(hepatitis A,dysentery and typhoid),5 diseases transmitted by body fluids(HIV,hepatitis B,hepatitis C,gonorrhea and syphilis),6 diseases transmitted by insects(brucellosis,malaria,schistosomiasis,encephalitis B,leptospirosis and anthrax).A common factor was extracted in each model.According to the common factors extracted,the fluctuation range of the incidence of humoral transmitted diseases is increasing year by year,while the common trend of the incidence of the other three types of infectious diseases is generally getting stable,and the fluctuation range is decreasing year by year.However,the incidence of respiratory infectious diseases was rising again from 2013.The common trends of TB incidence have been to decline in all economic regions,with the fastest decline in the six provinces lying in the north of the western region and the slowest decline in the six provinces lying in the south of the western region.The results of cross-correlation analysis showed that there is a lag with three periods for the influence of per capita GDP on the common factor of tuberculosis incidence in the north of eastern and the central regions,a lag with two periods in the south of eastern region,and a lag with one period in the north and south of western region and the northeastern region.A strong negative correlation was observed between the monthly GDP per capita and the regional common factors of tuberculosis incidence.If the monthly per capita GDP have an increase of one thousand yuan,the tuberculosis incidence(1/100000)would be reduced by 70.5% in the central region,by 34.4% in the south of eastern region,by 32.5% in the north of eastern region,by 18.9% in the south of western region,by 75.2% in the north of western region and by 45.3% in the northeastern region.Conclusion: Prevention and control of respiratory infectious diseases should continue to be strengthened to prevent the incidence from rising again.In addition,special attention should be paid to the prevention and control of humoral diseases in the period of spring time.Strategies for the prevention and control of tuberculosis can be formulated in different regions.The prevention and control of tuberculosis in the south of western region should be emphasized.There is a lag period of 1 to 3 months in the influence of regional economic level on the incidence of tuberculosis.In the south of western region and the eastern regions,in addition to economic factors,special attention should also be paid to the non-economic factors in the process of tuberculosis prevention and control.Dynamic factor model could extract the common trend of infectious disease incidence sequence,which is not observable directly.And there will be great space for the application of this statistical model in the field of medical research.